The present invention relates to the manufacture of getter wires for removing gaseous impurities such as oxygen, nitrogen, carbon monoxide, carbon dioxide, hydrogen and water vapor from evacuated spaces. Such wires are used in sealed evacuated devices such as cathode-ray tubes, power tubes and in various vacuum processes where a getter is flashed during the last stage of evacuation of various devices to clean up residual oxygen, nitrogen and other reactive gases. Usual getter materials are the reactive metals titanium, zirconium, hafnium and barium. Such wires may also be used as sources of metal vapors for thin film technology as well as merely as getters. In order to evaporate such metals, they are normally heated to a temperature in excess of 1800.degree. C. where the vapor pressure of the getter metal is extremely high. Since such temperatures are above the melting point of titanium and zirconium, the getter metal must be supported during its heating. One present commercial method of doing this is the provision of an alloy of the getter metal, such as titanium, with a refractory metal, such as tantalum (see U.S. Pat. No. 2,948,607 Wagener, Aug. 9, 1960) commercially available getter alloy is one of tantalum containing 20 percent (by weight) titanium. Such a wire can be can be heated to 2000.degree. C. and still retain its strength characteristics.
The manufacture of tantalum--20 percent titanium alloy is quite difficult. In arc melting, the large difference in melting point between tantalum and titanium (3000.degree. C. vs. 1680.degree. C.) and the high vapor pressure of titanium at the melting point of tantalum both cause segregation of tantalum (unmelted tantalum) and nonuniformity as well as accurate control of the percent titanium due to vaporization of titanium metal during melting. While these alloys can be made by powder metallurgical means, powders contain high amounts of interstitial impurities such as C, O.sub.2, N.sub.2 which usually results in brittleness and subsequent fabrication difficulties.